<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes" />
    <title>ShellCheck: SC1028 – In `[..]` you have to escape `\( \)` or preferably combine `[..]` expressions.</title>
    <link rel="stylesheet" href="css/bootstrap.min.css" />
  </head>
  <body style="margin-left: auto; margin-right: auto; max-width: 800px">
    <h1>SC1028 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC1028">See this page on GitHub</a>
    <p style="display: none"><a href="index.html">Sitemap</a></p>
    <hr />
    <h2 id="in--you-have-to-escape---or-preferably-combine--expressions">In
<code>[..]</code> you have to escape <code>\( \)</code> or preferably
combine <code>[..]</code> expressions.</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC1028.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="bu">[</span> <span class="ot">-e</span> ~/.bashrc -a <span class="er">(</span> <span class="ex">-x</span> /bin/dash <span class="at">-o</span> <span class="at">-x</span> /bin/ash <span class="er">)</span> <span class="ex">]</span></span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<p>In POSIX:</p>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC1028.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">[</span> <span class="ot">-e</span> ~/.bashrc <span class="bu">]</span> <span class="kw">&amp;&amp;</span>  <span class="kw">{</span> <span class="bu">[</span> <span class="ot">-x</span> /bin/dash <span class="bu">]</span> <span class="kw">||</span> <span class="bu">[</span> <span class="ot">-x</span> /bin/ash <span class="bu">]</span><span class="kw">;</span> <span class="kw">}</span></span></code></pre></div>
<p>Obsolete XSI syntax:</p>
<div class="sourceCode" id="cb3"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb3-1"><a href="SC1028.html#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">[</span> <span class="ot">-e</span> ~/.bashrc -a <span class="er">\(</span> <span class="ex">-x</span> /bin/dash <span class="at">-o</span> <span class="at">-x</span> /bin/ash <span class="dt">\)</span> ]</span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p><code>[</code> is implemented as a regular command, so <code>(</code>
is not special.</p>
<p>The preferred way is not to group inside <code>[ .. ]</code> and
instead compose multiple <code>[ .. ]</code> statments using the shell's
<code>&amp;&amp;</code>, <code>||</code> and <code>{ ..; }</code>
syntax, since this is well defined by POSIX.</p>
<p>Some shells, such as Bash, support grouping with
<code>\( .. \)</code>, but this is an obsolete XSI-only extension.</p>
<h3 id="exceptions">Exceptions:</h3>
<p>None</p>
    <hr />
    <p style='font-size: 80%'><a href="../index.html">ShellCheck</a> is a static analysis tool for shell scripts. This page is part of its documentation.</p>
  </body>
</html>


